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nutrients (fats (importance of fats
efficient energy source
solvent…
nutrients
During photosynthesis ,plants take in carbon dioxide and convert it into sugars and other biological molecules in the presence of sunlight . When animal eats plants ,these biological molecules will become part of the animal body . The major biological molecules are carbohydrates ,proteins and fats
fats
importance of fats
- efficient energy source
- solvent for fat soluble substances eg. vitamin A and vitamin D and hormones
- excess is stored in adipose tissues beneath the skin
- insulate the body
- essential part of protoplasm
Fats are made up of glycerol and fatty acids . The formation of lipids such as fats and oils involves the reaction between glycerol and fatty acids called condensation
organic molecules made up of the elements carbon, hydrogen and oxygen .
two types of fats
- Saturated fats that exist in solid form in room temperature. They include animal fats like butter and lard,and are linked to the clogging of arteries and heart attacks .
- Unsaturated fats which exists as liquids or oils at room
temperature . They include fish oil from salmon and
mackerel , and can reduce fatty deposits in arteries
emulsion test for fats
- Mix a sample of substance to be tested with 2cm3 of ethanol in a test tube. Shake thoroughly , and then pour the mixture into another test tube containing 2cm3 of water
- The mixture turns cloudy if fats are present
- The mixture remains clear if fats are absent
carbohydrates
importance of carbohydrates
- provides energy
- cellulose , a form of structural carbohydrate , is required in the formation of supporting structures eg ,plant cell wall
- require in the synthesis of lubricants
- substrate for respiration
- formation of amino acids , fats , DNA
- In animals , excess is converted to glycogen and is stored
in the liver and muscles as glycogen or in the adipose
tissues as fats . In plants ,excess is stored as starch in
roots and seeds
can be classified into
- monosaccharides ( glucose - grapes , fructose -fruits , galactose -milk )
- disaccharides ( sucrose-sugar cane , lactose -milk , maltose - cereals )
- polysaccharides ( starch-bread , glycogen-beef , cellulose-green vegetables )
Organic molecules made up of the elements carbon , hydrogen and oxygen
benedict’s test for reducing sugars
- Add 2cm3 of benedict's solution to 2cm3 of the substance being tested , in a test tube . Shake the mixture before immersing the test tube in a beaker of boiling water .
- large amount of reducing sugar --> a brick-red precipitate forms
- moderate amount of reducing sugar --> orange / yellow precipitate formed
- trace amount of reducing water --> green preciptate formed
iodine test for starch
- place sample on a white tile and add two or three drops of
iodine solution to the substance tested .
- if starch present, blue-black colour forms
- if starch is absent , iodine solution remains brown
condensation reaction
- it is a chemical reaction in which two simple molecules are joined together to form a larger molecule with the removal of one molecule of water
hydrolysis reaction
- it is a reaction in which a water molecule is needed to break up a complex molecule into smaller molecules
proteins
Organic molecules made up of elements carbon , hydrogen , oxygen and nitrogen
Proteins are made up of amino acids . Polypeptides are formed when molecules of amino acids are joined together to form long chains
importance of proteins
- formation of protoplasm for growth
- synthesis of enzymes
- production of antibodies
- formation of haemoglobin
- formation of bone
Sources of proteins include milk and other dairy products , various kind of meat , eggs , soya beans and soya bean products
biuret test for proteins
- Add 2cm3 of sodium hydroxide solution to the solution of the substance to the tested . Shake thoroughly and then add two to three drops of copper 2 sulfate solution one drop at a time to the mixture
- A purple / violet colouration indicates the presence of protein
- A blue colouration indicates the absence of protein
water
- a important solvent and forms a large part of the cytoplasm and the transporting medium ; blood , in humans
- essential for most of the biochemical reactions of the cell which can take place only in a aqueous medium
- the medium through which diffusion of oxygen and carbon dioxide takes place
- an important solvent for soluble nutrients from the digestive tract and metabolic wastes such as urea
- essential for plants to keep the turgidity of cells and to perform photosynthesis